New Build Log 1250 x 1250 CNC wood & cardboard

Have decided to go back to drawing board & start designs form scratch sell on previous attempt ! I have limited workshop tools but have access to cutting & drilling - may ask on here if some components can be machined but not at that stage yet - drawings attached ! Have been talking to Dean quite a bit, invaluable advice.

I want a cutting area of 1250mm x 1250mm – cutting sheet wood, cardboard mainly but want to do some 3d carving of wood at some point

Currently my Bed is 1500mm x 1500mmm approx

Think I’ll just ask you for advice & recommendations regarding components below

X & Y Axis RM1610 Ballscrew travel 1400mm approx

Z axis RM1605 350mm approx

Now some questions regarding the ballscrew

4x anti backlash ballnuts
4 x Support Units – which are best some balance between quality & price
4x couplings ?
Not decided mounting brackets any suggestions ?

Dimensions are guesstimates so can be adjusted as per final dimensions of Gantry & Z axis designs

Rails & carriages for X, Y & Z axis

HiWin type cartridge rails 20mm on X & Y axis, 15mm on z Axis correct me if
Mounted on profiles with T nuts every 60mm
What carriages & size of rails for each axis ?

Bed
Need to dicuss Bed with you assuming 18mm th MDF

Spindle
I have a Kress spindle and a Makita palm router I could mount or am I better going for another solution